Halo 4 Controller scheme

Ok. I was wondering what the control for Halo 4 would be since they added sprint to everyone and another AA of the players choice.

LT: Grenade Throw
LB: Jump
RB: Melee
RT: Fire

Joysticks: Move, Duck, Zoom

X: Sprint
A: Switch between grenades
B: Pick up weapons/ reload
Y: Switch primary weapon

Select: view score
Start: menu

D-Pad: Ordinances and possibly second AA.

So where should the second AA be on the controller?